This invention relates generally to remotely controlled, automated telephone system terminal boxes, such as pedestals, aerial terminals, and building terminals, typically used by telephone utilities to facilitate interconnection of telephone cable pairs. More particularly, the present invention relates to electronically controlled, remotely actuated switching of a non-blocking network for use by telephone companies in lieu of prior art manual pedestals, aerial terminals or building terminals.
Pedestals, aerial terminals, and building terminals are used extensively in the telephone outside plant industry to distribute service to telephone subscribers. A pedestal, aerial terminal or building terminal is generally used as the cross-connect point between a multi-pair (typically 25 pairs) telephone cable and the individual pairs of wires that lead directly to a telephone subscriber's location, such as a residence or small business. The pairs of wires in the multi-pair cable are referred to as distribution or F2 pairs or lines, whereas the individual pairs are referred to as drop or F3 pairs or lines. In a traditional aerial terminal, for example, the multi-pair cable is strung between telephone poles in an alley or along a road. Multiple aerial terminals are typically spaced along the cable route such that the drop pairs to a telephone subscriber's location do not have to travel far before reaching the nearest terminal. Inside the terminal, cross-connect points are provided that allow the drop pairs to be attached to many, or all, of the pairs in the multi-pair cable. In the interest of most efficiently using a given number of distribution pairs, the same distribution pairs are available for cross-connecting at several terminals along a route. This example is equally valid for locations utilizing building terminals, in which case the drop pairs are within a building, such as an apartment complex, and pedestals, in which case the distribution and drop pairs are buried, such as in a utility trench behind a residential subdivision.
Traditionally, pedestals, aerial terminals, and building terminals have been manually wired. Thus, when a cross-connect needs to be changed, a service person must be dispatched to the terminal location to move or add the particular cross-connect. This approach has generally been acceptable in the past, but as subscriber demand for more second line services has increased, so has the need for automation in this portion of the telephone network. An automated terminal must include a non-blocking network to ensure full utilization of the small number of distribution pairs that are typically available.
In the past, non-blocking networks have been generally uneconomical. Known electronically operated cross connect systems, such as that described in U.S. Pat. No. 4,833,708 to Goodrich, were limited in their ability to switch input/output telephone lines. The switching matrix of these prior art cross connect systems did not allow full use of the input lines because as the system became loaded, some of the input lines were blocked by the accessible input pairs already assigned to other output pairs.
It is therefore a principal object of the present invention to provide a remotely controlled multiple pair pedestal/building terminal (REPED) in which a multiple-position rotary switch is driven by a stepper motor and electronically controlled by a common feeder pair.
It is a further object of the present invention to provide a remotely controlled multiple pair pedestal/building terminal that incorporates a feeder pair contention circuit for permitting a single feeder pair carrying both power and control signals from the central office to electronically control a multiplicity of remote pedestals/building terminals.
It is a further object of the present invention to provide a remotely controlled multiple pair pedestal/building terminal that incorporates a continuity test circuit for facilitating 100% testing of connections between input and output telephone lines, the continuity test circuit being designed such that even while a continuity test is being performed on an active line, the user is unaffected and will not notice the test being performed.
These and other incidental objects are accomplished in accordance with the illustrated preferred embodiment of the present invention by combining a plurality of stepper switch blocks, each of which includes a high resolution stepper motor, a switch arm assembly, and a multiplicity of contact pads arranged in two concentric circles on a printed circuit board. The high resolution stepper motor is employed to position the switch arm assembly on contact pads representing a desired output telephone pair. The number of steps executed by the stepper motor is determined by a software algorithm based on the size of the system. A large output complement, for example, requires more switch contact pads on the printed circuit board and fewer steps between contact pad positions. A stepper switch block may be replicated to construct a square or rectangular matrix of input and output telephone pairs. The number of switch contact pads determines the size of the remotely controlled multiple pair pedestal/building terminal system being constructed. In the case of a square switching matrix, the number of contact pads on each stepper switch block is equal to the number of switching blocks in the system. Rectangular switching matrices may be built with an unequal number of pads and switching blocks. The switch arm assembly or rotor of each stepper switch block is connected to an input distribution telephone pair.
Two additional stepper switch blocks and their associated driver circuits comprise the continuity test circuit that is employed to accomplish continuity testing. The continuity test circuit reduces the reliability required of each stepper switch block, since feedback is available to make minor adjustments to the number of steps executed by the stepper motor. In this way the switch arm assembly or rotor may be positioned at the center of each of the switch contact pads on the printed circuit board.